Coconut Milk - This is full-fat, regular coconut milk, which comes in cans or little aseptic packages, NOT milk beverage (in the big cartons). If you need to use light coconut milk or coconut milk beverage in the frosting, just add 1 tablespoon at a time, until your desired consistency is reached. Light coconut milk may work in the butterscotch sauce, but we haven't tested it.
High Altitude Adjustments - Above 4000 feet, reduce the baking powder to ¼ teaspoon and optionally reduce the brown sugar to ⅔ cup. To keep them from ending up too greasy, I recommend also cutting the buttery sticks by 1 to 2 tablespoons (they have little markers on them!), and consequently increase the milk beverage by 1 to 2 tablespoons. You may need to increase the baking time to 23 to 25 minutes.